The DC machine has two main parts: the stator and the rotor. The stator and rotor are separated by the air gap. The stator is the part of the machine that has no movement, that is, it is stationary. https://www.mrosupply.com/lighting/lighting-fixtures/led-lighting-fixtures/5871806_seal4-50d10_rab-lighting/ The rotor is the moving or rotating part. Both stator and rotor are built with ferromagnetic materials. This is necessary to raise the flow density and thus decrease the size of the machine. In the DC machine the field winding is in the stator and the armature winding in the rotor.
The conductors inserted into the stator or rotor channels are interconnected to form the windings. The winding at which the voltage is induced is called armature winding. The main operating principle of a DC motor is based on the electromagnetic force that acts on each conductor immersed in a magnetic field, when an electric current will circulate over it. Since the force acting on each conductor is at a distance R (radius) from the center of the rotor, the sum of the contribution of all the conjugates will give rise to the torque of the motor.